C8H4O4

C8H4O4 is the molecular formula for several chemical compounds, most notably phthalic anhydride and maleic anhydride. Phthalic anhydride is a white solid and a cyclic anhydride of phthalic acid. It is a significant industrial chemical, primarily used as a precursor in the production of plasticizers, particularly for polyvinyl chloride (PVC). It is also used in the manufacturing of polyester resins, alkyd resins for paints and coatings, and certain dyes. Phthalic anhydride is produced industrially through the catalytic oxidation of o-xylene or naphthalene.

Maleic anhydride, also a white crystalline solid, is the anhydride of maleic acid. It is an important building block in organic synthesis. Its main applications include the production of unsaturated polyester resins, which are used in fiberglass-reinforced plastics for boats, automobiles, and construction materials. It is also used in the production of lubricating oil additives, agricultural chemicals, food additives, and copolymers. Maleic anhydride is manufactured by the catalytic oxidation of n-butane or benzene.

While C8H4O4 represents both phthalic anhydride and maleic anhydride, their distinct structures and functional groups lead to different physical properties and a wide range of applications in various industries. The industrial production methods and the scale of their respective markets highlight their importance as commodity chemicals.